Wheat sedimentation values and falling number

Abstract

The quality of food wheat is affected by many factors, particularly variety, locality and growing conditions (weather, agricultural engineering, fer-tilisation) and furthermore by harvesting method, postharvest treatment and storage. Thereby it is possible to explain the differences in the technological quality of wheat industrially manufactured in various regions, various years and also during storage in agricultural operations. Technological quality of wheat for the milling and baking use is determined by the protein quantity and quality and the state of the carbohydrate -amylase complex, thus the degree of starch damage and amylase content. The determination of these features in both the cultivation process and manufacture is carried out by common standardised methods, the results of which are the main indicators of wheat quality-protein content, sedimentation values (SDS and Zeleny test) and falling number. These parameters influence the qualities of mill and baker's products in a decisive way. In order to achieve their standard quality in established continuous manufacturing processes in mills and bakeries the stable quality of input commodities, i.e. of wheat and its flour, is preferably required. Quality characteristics of wheat flour significantly correlate with corresponding wheat characteristics, nevertheless the milling process affects their absolute values. For example F����� (2002) quoted the Abstract H������� M., Š������ V., B����� J. (2004): Wheat sedimentation values and falling number. Czech J. Food Sci., 22: 51-57. Technological quality of wheat from 2001 and 2002 harvests and its changes in the course of one-year storage were evaluated using protein content, SDS and Zeleny tests and falling number. Average values from the analyses of ten partial samples that were taken from five Central Bohemian producers (beet-producing region) during the period of eleven months (from October to August) characterise wheat standard quality for the mill processing and it is possible to explain their variations by the effect of the harvest year in the comparable wheat variety composition. With regard to similar climatic conditions of the years 2001 and 2002, there were not found any marked differences in protein content (2001-average 12.4%, 2002-average 12.8%) and Zeleny test (2001-average 52 ml, 2002-average 55 ml) but the falling number was significantly different (2001-average 321 s, 2002-average 287 s). During the storage time in agricultural operations no conclusive changes in protein content were found though protein quality slightly decreased according to the SDS and Zeleny test values. Falling number values of wheat from 2001 harvest slightly increased, which was not evidential for the set of samples from 2002. Statistically significant correlations were calculated between the falling number value of wheat and its laboratory-manufactured flour in both harvest years (r = 0.556 in 2001, r = 0.825 in 2002). The value of Zeleny test significantly correlates with SDS test (r = 0.531 in 2001, r = 0.787 in 2002) as well as with protein content.